Compensating thermal switch operating means



J. F. FRESE COMPENSATING THERMAL SWITCH OPERATING MEANS Filed Feb. 18', 1933 jMAA A ril-24, 1934.

Patented Apr; 24, 1934 COMPENSATING THERMAL SWITCH OPERATING MEANS Joseph F. Frese, Baltimore, Md., assignor to Monitor Controller Company, Baltimore, Md., a corporation of Maryland Application February 18, 1933, Serial No. 657,419

3 Claims. (01. 200-122) This invention relates to thermally operated fiat iii-metallic strips 2 and 3, respectively, the circuit controlling devices, and particularly to tubes being of the same diameter and length and a compensating thermally responsive element the strips being oppositely coiled, shown. The which will operate the same under all changes tubes are arranged end to end and are coupled in atmospheric temperature. The type of therto one another by a short plug 4 of non-metallic mally responsive element to which the present material which is a poor conductor of heat, such invention relates is that shown in patent to as bakelite. The adjacent end turns of the tubes George H. Whittingham No. 1,627,816, dated May are securely fastened to this plug by rivets 5. A 10, 1927, comprising a flat bi-metallic strip heliwasher 6 which may be of bakelite, fibre or other cally coiled to form a tube or housing, this tube heat insulating material, fits around the plug 5 having its lower end open and secured to a suitbetween the ends of the tubes and projects latable support, while its upper end is closed and erally beyond the tubes, this washer serving to free to turn. A heating element, comprising a deflect warm air currents arising from the lowpart of the circuit controlled by the switch, is er tube 11 away from the upper tube 2).

insertable into the tube through its lower end, The base and the elements thereon are, in prac- 7 and the heat generated by the current in the tice, vertically arranged, as shown. One end of heating element causes the tube to partly uneach element is fixed while the opposite end is coil to operate a switch. This device is afiected free to turn. As shown in the drawing, the lower in its operation by the temperature oi the surtube b is secured at its lower endfas by solder rounding atmosphere. In order to compensate or brazing 7, to the horizontal foot 7 of a metal 7 for changes in atmospheric temperature, I add Supp Strip 7 which is Secured the as to the tubular device just described, having a This foot has an opening '7 registering with the heating element, a similar but oppositely coiled lower open end of the tube and through which a tube which is without a heating element and heating element 8 may be inserted in the tube.

which is rigidly connected to the upper end of This heating element, as shown, consists or a wire the first mentioned device by a heat insulating doubled upon itself and having its ends secured joint which closes communication between the to binding posts 9 and 10 to which terminals of tubes. Preferably also a device is placed at the an electric circuit may be connected. A metal joint to deflect warm air currents arising from cap-piece 11, secured to the uppermost convolu-- 30 the lower tube away from the upper tube. As tion of the tube 1) has a central opening, and a both tubes are affected by atmospheric temperaguide pin 12, threaded into a forwardly extend ture, but are oppositely coiled, a switch arm aring end 13 of a metal strip 13 extends into this ranged on the upper end of the upper tube will opening. This strip is secured to the front of not be moved by reason of changes in atmospheric the base 1, as shown, and the pin carried by the temperature, but only by changes in temperature strip prevents lateral displacement of the upper caused by the heating element in the lower tube. end of the element. The cap-piece has a later:-

In the accompanying drawing, ally projecting arm 11 at the outer end of which l is a front elevation of a circuit brealzis a flat disk 11* for tripping the circuit breaker.

er, partly in section, illustrating the invention; The element A is identical in construction with 40 Fig. 2 a right side elevation of the same; the el rent B, except that upper tube a is cp- Fig. 3 is a section on the line 3 3 of Fig. l, posits. round with respect to the tube 22 and its d, lower tube a is oppositely wound with respect Fig. 4 is a section on the line i i of Fig. i. to 'ube Z3. and the arm ii on the element Referring to the drawing, 1 represents a 5 etc to the right, in F g. 1,. while the corof insulating material and and B i a Farm 4311 e18 1 35 3 m m0 dicste thermally responsive elements, each ads; figure. dislrs on these arms er;- ed to curate a circuit breaking switch .3 These I." plug let 1' 14 of the circuit nate t element er their adjacent ends, 1 "r are n sed to the surrounding ch: 1 a mospheric tempera ture which would cause the lower tube to twist in one direction would cause the upper coil to twist in the opposite direction to the same extent, and hence, the position of the arm 11* and disk ll will not be affected by changes in atmospheric temperature. If the lower tube is heated by current in the heating element 8, this tube will untwist and rotate the upper tube b, which is not heated, and the arm l1 on the latter tube will swing toward the tripping lever 14, and if the lower tube is sufiiciently heated, the lever will be moved to trip the switch.

The heat generated in the lower tube by the heating element is not transmitted to the upper tube because the plug or coupling member 4 closes communication between the tubes and holds them apart from one another, and the washer 6 deflects warm air currents flowing up around the lower tube away from the upper tube.

The operation of the element A is the same as that 01 the element B, except that being placed on the opposite side of the circuit breaker, its tubes are coiled in the opposite direction from the corresponding tubes of element B.

The elements A and B may be usedto operate individual switches of any kind, but for the purpose of illustration, I have shown them arranged to operate the same circuit breaking switch, which is arranged between them near their upper ends. It is necessary to have one end of each element secured to a flxed support and the other end free to turn. In the illustration, the lower ends of these elements are fixed and the upper ends are free and this arrangement is preferred, but it is obvious that if the upper ends were fixed and the lower ends were left free to turn, the result would be the same and arms connected to the lower elements might be used to operate the switch by suitably locating the latter.

The switch mechanism shown in the drawing comprises a stationary contact member 15, mounted on the base 1, and a spring contact arm 16 is secured to a cross-piece 17 on a resetting lever c. Ihis lever comprises a sheet metal crosspiece 18 having a handle 19 secured to its central portion and having at its ends two parallel arms 20 which are pivoted to ears 21 projecting outwardly from a sheet metal plate 22 which is secured to the front of the base 1. The crosspiece 17 is secured to the lower edges of the arms 18 and the spring contact member 16 is bent into U-form and fits around the inner edge of said cross-piece, the end 16 of the member being turned downwardly near the outer edge of the cross-piece to form a stop for the tripping lever 14. The tripping lever has ears 14 at its opposite edges which are pivoted to ears 23 projecting outwardly from the plate 22. A spring 24 between the lower end of the tripping lever and the plate 22 presses the upper end or the lever toward the stop 16* and when the switch is closed, this upper end engages the cross-piece 17 of the resetting lever and keeps the switch closed. When the lever is moved by either of the thermally responsive elements, the upper end of the lever is disengaged from the cross-piece l7, and the switch then drops open. The tripping lever has fingers 14 with flanges 14 at their ends which project toward the disks 11 of the thermally responsive elements and the disks are adapted to engage these flanges.

What I claim is:

1. In a circuit-controlling device, a suitable support, a compensating thermally responsive element comprising two tubes and a heat insulating joint connecting said tubes end to end, each tube composed of a helically coiled bi-metallic strip, the strips of the different tubes being oppositely coiled, said element being vertically arranged on said support and having one end fixed thereto, the other end being free to turn, the lower tube having its lower end open and its upper end closed, and an electric heating element insertable into the lower tube through its open end.

2. In a circuit-controlling device, a. suitable support, a compensating thermally responsive element comprising two tubes and a heat insulating joint connecting said tubes end to end, each tube composed of a helically coiled bi-metallic strip, the strips of the diiierent tubes being oppositely coiled, said element being vertically arranged on said support and having one end fixed thereto, the other end being free to turn, the lower tube having its lower end open and its upper end closed, a heat deflecting disk projecting laterally from the element adjacent said joint, and an electric heating element insertable into the lower tube through its open end.

3. In a circuit-controlling device, a suitable support, a compensating thermally responsive element comprising two tubes and a plug of heat insulating material fitting within and secured to one end of each tube, thereby connecting the tubes end to end, each tube composed of a helically coiled bimetallic strip, the strips of the diiierent tubes being oppositely coiled, said element being vertically arranged on said support and having one end fixed thereto, the other end being free to turn, the lower tube having its lower end open and its upper end closed by said plug, a heat defleeting disk mounted on said plug and projecting laterally therefrom between the tubes, and an electric heating element insertable into the lower tube through its open end.

JOSEPH F. FRESE. 

